1. Field of the Invention
The invention relates to a method of initiating an operation in dependence upon the combined mass of an element and matter which is in or on the element. The invention also relates to a method of removing material from a driven element, and to a control means.
2. Brief Description of the Prior Art
The invention is concerned with the operation of a driven element wherein, during operation, there is an interchange of matter between the element and matter which flows through or over the element. An example of such an operation would be one in which matter flows through the element and a proportion thereof collects in the element during such operation. It is necessary periodically to carry out an operation upon the element such as the removal of matter which collects therein. In the past it has been necessary to stop the element in order to determine whether the element has reached a suitable stage in its operation for the initiation of such an operation.